Performance and failure mechanisms of screw-reinforced glulam connections with slotted-in steel plates
Abstract
Self-tapping screw (STS) reinforcement can delay splitting in timber connections, but its effectiveness under reversed-cyclic loading depends on connection geometry. In this study, 71 full-scale tests on Black spruce and Douglas fir glulam dowel-type connections with one or two slotted-in steel plates loaded parallel to the grain were examined. Two layouts were investigated: a ductile layout with large fastener spacing (7d) and Ø12.7 mm dowels, and a brittle layout with small spacing (5d) and larger Ø20 mm dowels. Monotonic and reversed-cyclic tests showed that reinforcement benefits varied with dowel slenderness. STS stabilized the monotonic post-yield response at high slenderness (λ > 8.9), improved resistance and displacement capacity at moderate slenderness (5.3 < λ < 6.3), and increased resistance at low slenderness (λ < 3.6). Under reversed-cyclic loading, splitting and dowel fatigue failure modes were observed that were not predicted by the Canadian Standard for Engineering Design in Wood (CSA O86). Comparisons of continuous and cut dowels supported a rope-effect contribution to post-yield hardening. Based on the observations, a preliminary framework is proposed to support the development of CSA O86 design guidance for STS reinforcement of glulam dowel-type connections loaded parallel to the grain.
Reference
Christopher Gagnon; Thomas Tannert; Alexander Salenikovich. (2026). Performance and failure mechanisms of screw-reinforced glulam connections with slotted-in steel plates. Elsevier BV. https://doi.org/10.2139/ssrn.7583745
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